Accelerator target holder



Feb; 23, 1954 C. M. GORDON ET AL ACCELERATOR TARGET HOLDER Filed Nov. 26, 1952 2 Sheets-Sheet 1 ATTORNEY.

Feb. 23, 1954 Filed Nov. 26, 1952 C. M. GORDON ET AL ACCELERATOR TARGET HOLDER 2 Sheets-Sheet 2 FIG.4

INVENTORS. CARROLL M. GORDON CHARLES ACORUM A TTORNE Y.

Patented Feb. 23, V1954 UNITED STATES; PATENT oFFlfcE,

ACCELERATOR TARGET HOLDER Carroll M, Gordon, San Pablo, and Charles A. Corum, Berkeley, Calif.,assignors to lthe United StatesV of Americav as represented by the United States AtomicA Energy Commission v Application November l26, 1952, Serial N'o. 322,654 14 Claims. (Cl. Z50-49.5)

This invention relates `to particle accelerators and more particularly to apparatus' employed therewith for the purpose of accurately 'positioning; target material in the path of. the beam..

the irradiation ci small samples in a cyclotron or other accelerator, it hasbeen found convenientv to dispose such samples Within a metal foil. container having the shape of a relatively flatl dish. In providing a mechanism for mounting the dish in. the path of the beam, several problems are. encountered. Itv is important that such mechanism permits rapid removal of the material following, irradiation, since many such target materialsv exhibit a brief half-life (rapid loss of radioactivity)` andl thev interval of exposure of the. operator should be a minimum.

In use portions of the mechanism adjacent the target: become radioactively contaminated so that their replacement necessitates. due consideration to-the;simplicity.and cost. factors as well as inter-- changeabi-lity of such parts. In addition to the foregoing requirements, means must be providedv for 1the circulation of coolant through as much of'rthe entire .apparatus as Vpossible'.

'TheV present invention therefore isan improvedv target apparatus characterized by the named advantages and which are more specifically identidad iin the. :following objects.

'It is accordingly aprincipal object. oftheinuentionto :provide accelerator target apparatussthazt may be quickly .positioned iioi` irradiation. :adjaf cent-accelerator structure and-asfreadiflyremoved therefrom- Anotherk object .of the invention .is to .provide accelerator target. apparatus-.havingauidzcooled portionforzrelatively permanentgmountingonthe accelerator wall/structure :and a target holding. and iflui'd'cooled portion which is quickly removable. from- Isaid first. portion.v

4another object of4 the -invention to: provide a generally two-component target apparatusxin which the.y removable :component isf alwayspprealigned whenfiniassemhledi relation `withine.fixed component.

.A'furtheriobjectistprovid'e acceleratorztarget apparatus including a stationary, vacuum-.tight componentfadapted `toibo mountedion theaccelcrater Wall: and a removable. targetbearing:com-` ponent finsertable. .therein and .surrounded by a circulating fluid.;coolant.,

An additional-Objectis: to :provide a removable target holder including- :relatively .movable memm bersadapted tozform and-fseal disk'. elements finto ai substance enelosingzcontainer;tomaintain. said a. predetermined 1alignedposition of' 5.5

2. irradiation and. upon. subsequent relative inlovement of-said :members to release saidl container for gravity discharge;

Othervobjects and vadvantages ofthe invention. will be obvious ,and will ybe apparent from the. folios/ving specification and acompanyingl drawl ings. wherein t Figure Vl; is aside view chiefly section yshow-- ingv the target apparatus of this invention position upon vthe wall of a cyclotron tank, for example;`

Figz. ZP-isa vertical. sectional'View taken on line: 2--12'v of. Figi. l;

3 is .a topfview of Fie.. partly in section as .indicated by line; .3,-F3- of the latter gure;

Fig. 4 is an end elevation of Fig. 1 as viewed from :the :right side of the. latterf-andffsomeir/ hat reduced .in scale ;v andi Fig. 5. is a ,side view Aof the removable portion of: the targetv apparatus ciali-ia 4 .as viewed from the 'left side thereof.

The design of the individual -cozfnponents .and their functional relation, will b e `more readily appreciated by considering rstthe removabletarget. carrier ,of 'the .target apparatus shown per sein Fig. 5 andin position with. the stationaryv components -for irradiation .in the remammg. lign-res which depict, particularly in the sectional views, 'th-e details: of construction.

Accordingly', Eig. l :such target carrier' is. shown as including a. l.cylindrical mandrel 5 A.se-

curedf. as lby engaging threaded surfacesA to: fa

cylindrical mandrel body y(i .of Aslightly ,greater diameter, the A.two kparts named presenting a continuous .cylindrical bore on the* inner surfaces thereof; `The end of. mandrel lopposite the body 6 is formed with an integral cap .porti-cnil: which is aperturedI for a .diameter somewhat lessv than :that ofthe continuous inner bore referred to above, and is inwardly :shouldered at v.Il `to provide a mandrel ledge for a purpose later to be describedr smoothly :fitting Within the inner bore offmandrel -.components 5 and'y -6 iis an inner cylinder '8, fthe inner end ici. lwhich. Yadjacent, the ledge '.8 lis .ont :away at :a suitable angiey .to form aswaging surface Hladapted upon travel of lthe cylinders tothe-,lemas shownl in Fig-1, andin-to peripheral 4engaeement with a. pair of foil disks disposed between surface I0- and vledge '81to deform .the circumferenceof said .disks and effect a seal thereby. Anannular seal Il surrounding cylinder 9- and.- dsposed in 1a suitable recess-in mandrel. body f6.' precludes ythe loss of vacuum through .these inter-fitting cylindrical lsurfaces as' will later appear,

For retracting cylinder 9 from the mandrel components and 6, there is provided a crosshead I2 having a seal receiving annular recess I3 surrounding a central bore extending inwardly from one end thereof. Such bore is peripherally stepped to receive a similarly stepped outer end of cylinder 9 around which the seal in recess I3 exerts sealing pressure; also an adjacent outer stepped portion of greater diameter receives a correspondingly threaded portion of cylinder 9, the two parts when assembled as shown in Fig. 1 constituting an essentially hermetically sealed unit. Transverse bores I4 and I5 are provided in the cross head I2 and lead from suitable integral external conduits IB and I1 to the interior of cylinder 9, bore I5 communicating with the open-ended tube I8 which is axially mounted in crosshead I2 for the continuous circulation of a coolant such as water therethrough.

Crosshead I2 is provided with a portion adapted to have mechanical connection with suitable actuating means; such portion may have the form of an integral tongue I9 extending diametrically thereacross and for a sufficient axial extent as to provide the connection mentioned. The latter preferably has the form of a bar 25 bifurcated at its upper end to receive tongue I9 and pivotally connected thereto as by pin 2| secured in one of the bifurcations by set screw 22.

Closely surrounding the outer portion of mandrel body 6 is a suitably apertured handle 23 extending downwardly in generally parallel relationship with bar 20 and rigidly united to body 6 by suitable means such as an elongated set screw 24 threaded into the surrounding portion of said handle.

Interconnection of bar 20 with handle 23 to effect lateral movement 0f inner cylinder 9 may be accomplished as follows. Handle 23 and also bar 29 are provided with elongated central slots 25 and 25 to receive the opposite ends of a link 21, which ends are suitably pinned to the adjacent handle and bar at 28 and 29 and retained by respective set screws 30 and 3l. A compression spring 32 may be confined between the central portions of bar 29 and handle 23 by any suitable retainers, such as the inwardly extending disks 33, welded for example, to these members. Pivoted on a pin 34 extending transversen ly of bar 29 below spring 32 and retained by set screw 35 is a distance piece 36 in the form of a bell crank, the shorter leg of which terminates in a curved contact surface 3l and the longer leg 38 of which, in the position shown in Fig. 1, is disposed in the plane of bar 29 and may be retained in such position by means of a knurled set screw 39 threaded into bar 23 so that its inner end frictionally engages leg 33. A bell crank shaped stop 33 having its longer leg I extending in general parallelism with handle 23 has its shorter leg :i2 disposed in a slot 43 in handle 23 and is retained therein by a pivot pin 44 secured' A stop screw in such handle by a set screw 45. i5 threaded into handle 23 above the slot 43 and in alignment with leg 3B and transversely of ther upper end of leg 4I is provided with a slotted head, as shown,'for arcuate adjustment of the leg 4I which serves to precisely vary the spacing between the lowerV end of handle 23 and that of bar 29 as to which reference will later be made.

Prior to proceeding with an explanation of the clamping action upon the superposed disks pre viously referred to, it is desired to call attention.

to a Structural feature of considerable signicanoe in the machining of the lleft end of man-l drel 5, as shown in Fig. 2. It will be observed that the wall of mandrel 5 slightly to the right of cap portion l and ledge 8 has been slotted to provide an entrance and exit passage 41 for the disks mentioned earlier and the formed container, respectively; such passage may be about any radius of symmetry but is peripherally about such a radius extending'normally to the plane of bar 2li and handle 23 so that the disks may be loaded and following irradiation discharged from a position to one side of the device as a whole. Further such passage, as will be seen in Fig. 2, is of such arcuate extent as to comprehend a proiected diameter so that the width of the slot for its entire length radially of mandrel 5 is that of a diameter thereof. From the foregoing, it will be seen that when the removable component of the target apparatus (Fig. 5) has been removed from its position of irradiation adjacent the accelerator wall (Fig. l), knurled screw 39 may be rotated to release bell crank leg 38 and the latter then swung counterclockwise to the dotted line position shown.

Thereafter on bringing bar 2D to a positionl approaching handle 23 and thereby compressing spring 32 the inner cylinder 9 will move outwardly, Fig. l, leaving a space between the end thereof and ledge 8 0f mandrel 5. A receptacle in the form of a shallow dish 48 may now be introduced into peripherally supported position upon the swaging surface I9 of inner cylinder 9, the material to be irradiated having been previouslyplaced in said dish or immediately thereafter following insertion. A fiat cover disk 49 is then inserted into the mandrel 5 through the passage 4l and the manual pressure which confines bar- 29 and handle 23 in their dotted line position, Fig. 5, is now released, allowing the swaging surface I8 to closely approach ledge 8 and thereby clamp or seal the peripheral portion of dish 48 to the adjacent portion of disk 49. Adjustment of stop 45 prior to this operation is necessary when the thickness of the foil, for example, is dilerent from that employed in previous operations. It will be appreciated that the clamping action should not be excessive or an imperfectseal may result.

In positioning the portable target component above described so that the same will be in accurate alignment with the beam of particles and thereby irradiated, in addition to the alignment requirement it is desirable that the temperature gradient between the cyclotron wall structure and the portable target holder is as great as possible. Accordingly, provision has. been made in the design of the stationary component of the target apparatus which is mounted on the cyclotron wall for the maintenancegof; three temperature Zones decreasing in value from the cyclotron tank outwardly. In the embodinient illustrated herein it has been found ex. pedent to provide three concentric structures which are disposed in relatively rigid insulating relationship and each of which has such positive coolant provisions as experimentation has been found to be necessary.

Referring therefore to Figs. 1 and 3 of the.; drawing, it will be observed that there has been;i provided an innermost collimating plate 50 ofF somewhat massive proportions disposed invacuum tight relation against the face of the tank 52 and bolted thereto by peripheral bo1ts- 53 passing through suitable flange apertures and thence into threaded recesses in the tank. Anannular sealing ring 54 of suitable insulated may.

teria!! disposed in a correspondingrecess the face of plate 501 adjacent tank 52 insures a vacuum tight seal thereagainst. Centrally of ccllimati'ng plate 510 there is provided a collimating exit aperture 55 defined byy an inverted cone 55 extending outwardly for a substantial distance and bounded by an outer cylindricalwall 515i This latterV wally furnishes an addition-ali continuous surface through. which an. adjacent intermediate ila-nge plate 58 may be herinetical-lyl sealed through a suitable annular gasket 59 disposed a corresponding recess ins an inner cylindrical bore of said plate 58 corresponding in diameter to. said: cylindrical wallr 5Fl. said. intermediate plate- 518 has` also` a peripheral surface disposed in: a. plane paralleli with the surface ot' tank 5.2 whichA is closely maintained' against the parallel. outer surface of collimater plate 5U- by means oi bolts4 62 passing therethrough into'v threaded recesses in such collimating plate, there being an. intermediate circular gasket. |53A disposed in vacuumetight relation between the closely abutting plate. surfaces. As will be seen` in Fig. 1,v intermediate flange plate 5BV is` cut away ad jacent the proximate wall of collimating plate 50 for a. substantial radial extent beyondk the cylindrical boundary of conel 5S and such` space' provides a coolant chamber for the spaced metal'- lic. surfaces which is connected through passages E4 and. 65 with external' conduits 65' and 61. through whichr cooling water may be circulated. Thus it will be seen that: intermediate flange plate 58 will be maintained at a lower temperature than that of the. cyclotronv aperture adjacent` collimating plate 5l).

Adjacent intermediate plate 58 and maintained in vacuum-tight relation therewith is an` outer flange plate which provides two additional zones of reduced temperature gradients. Such outer flange plate, which is indicated at 63 on the drawing, isV spaced' from intermediate plate 58 by an annular ring 69 of resilient insulating material having an I-shaped cross section, the oppositely disposed recesses of which provide seats for' appropriate annular vacuum seals T0', while. av third seal is disposed in surrounding relation. tov insulator 69 and, in turn, isv seated in a U- shaped annular recess TIS of the outer flange. plate.

A desirable feature of the invention resides in a pair of spaced vacuum-tight windows 13 and 74 made of metal foil, for example, the inner window 'i3 of which has its peripheral portion sealed by contact with adjacent annular ring 10, while a similar ring 'l5 seated in a recess in plate 68 similarly seals the outer window. A ring-shaped spacer 76 provided with diametric bores leading into the space between the windows 13 and 74 and aligned with bores 'Il and 18 in plate 68 may serve conveniently to convey helium gas to the space between such windows and at a somewhat higher pressure than that of the water circulated through the intermediate flange plate in order to lessen the likelihood of damage to the vacuum seals mentioned. Outer flange plate 6B is suitably secured to intermediate flange plate 58 by suitable spaced bolts 19 threaded into recesses in plate 58 and surrounded by cylindrical type insulators within the apertures in plate B8 as will be seen in Fig. 3.

Outer flange plate 68 is also provided with a radial bore 8l through which helium gas at a somewhat higher pressure than that in bore TI may be supplied by an integral conduit 82 into the interior of the central cylindrical bore 83 into 6 which themandrer body si is received. as@ Fig. 1*. sacri helium sup-ela is not intended to provide the cooling effect of the arrangements` rei-established# as needed.

R'eferel'iV e is' now 'Iii-ade 'to the'- lii'ans'fo 'secure ing the removable component of the targetailef paramsl within the centralbore 83;, as vshow-n in Fig?. 1.. arrangement nay col-lvlieltly take: the forni 'of' air integral or attached ear 8ieltal tending outwardly from' thek peripheral; (yl cali wall' of' 'outer 'flange plate 'B8 'and prov ded With an aperture the-etll'('nlgliiA of Slightly grat'el" diameter' than set screwV'Z-f. 'It' is preferable tol out' away' the lateral wall of ear 84 to providea; passage merging with the named aperture. toi provide ingress for the set sc'z'rewy 24 into the slot thereby formedl and in this way to definitely es` tablish the rotative position. of irradiation of the portable assembly as described.

It is further desirable to prevent'loss of' heliliiifl gas through the cylindrical surfaces of cuter flange plate 68 and mandrel body 6 by disposing a vacuum seal-ing ring 85 in a suitable recess contiguous the central bore 83, as shown in Figure l.-

Accordingly, the inventionl is not intended to; be limited to the' embodiments as shown, but on the contrary is intended to cover suchi'iodiii'cae tions' and changes `as are comprehndedf within the'ls'cope of the appended claims.

What isl claimed is:

'1. Accelerator target apparatus comprising a fluid-cooled, beam collimating ila-nge assembly adapted to be` hernietically mounted on the exit' wall` of'an accelerator, said assemblyincluding' a relatively massive, conically apertured Wall flange adjacent the exit beam of said accelerator, an interrnediateA flange plate maintained in periph# erallysealed' relationA with said wally flange and having asubstantial surface area nearest the lat= terflange, sufficiently spaced therefrom to proef' vide a coolant chamber; and'conduit means corr: nected tov saidchamber for thev circulation of ailuid coolant therethrough.

2. Accelerator target apparatus comprising a' fluid=cooled3 beam`v collimating flange assembly adapted to be hermetically mounted on the exit wall of an accelerator, said assembly including a relatively massive, conically apertured wall flange adjacent the exit beam of said accelerator, an intermediate flange plate maintained in peripherally sealed relation with said wall flange and having a substantial surface area nearest the latter flange, sufficiently spaced therefrom to provide a coolant chamber, and an outer cylindrically apertured flange plate insulatingly secured to said intermediate flange plate.

3. The combination of elements deilned in claim 2 and including fluid conduit means connected to said outer flange plate for the circulation of a fluid coolant therethrough.

4. The combination of elements defined in claim 2 and including a pair of thin-walled foil sheets disposed in parallelism across the cylindrical aperture in said outer flange plate, means for peripherally sealing said sheets and fluid conduit means communicating with the space between said sheets.

5. The combination of elements defined in claim 2 and including an annular insulating seal o! substantial axial and radial extent disposed between said intermediate plate and said outer plate.

6. Accelerator target apparatus comprising a fluid-cooled, beam collimating flange assembly adapted to be hermetically mounted on the exit wall of an accelerator, said assembly including a relatively massive, conically apertured Wall ilange adjacent the exit beam of said accelerator, an intermediate flange plate maintained in peripherally sealed relation with said wall liange and having an annular recess in a plane surface normal to the aperture of saidwall ilange and remote from the latter, an annular insulating seal adapted to resist both axial and radial pressure disposed in said recess and an outer, cylindrically apertured flange plate having an annular extension disposed in said recess in pressure transmitting relation to said seal and means disposed peripherally of said outer ange plates for uniting the same into a relatively rigid assembly.

'7. The combination of elements defined in claim 6 and including a pair of thin-Walled foil sheets disposed in parallelism across the cylindrical aperture in said outer flange plate, means for peripherally sealing said sheets and fluid conduit means communicating with the space between said sheets.

8. The combination of elements dened in claim 6 and including a generally cylindrical target holder disposable in hermetically sealed relation in the cylindrical aperture of said outer flange plate. 9. The combination of elements deiined in claim 6 including target holder retainer means integral with said outer flange plate, and a generally cylindrical target holder disposable in hermetically sealed relation in the cylindrical aperture of said outer flange plate and maintained in irradiating position by said retainer means.

l0. The combination of elements dened in claim 6 including target holder retainer means integral with said outer flange plate and projecting outwardly therefrom, and a generally cylindrical target holder disposable in hermetically sealed relation for a substantial distance into the cylindrical aperture of said outer ange plate and maintained in irradiating position by said retainer means.

11. In accelerator target apparatus a target foil disks inserted therebetween, said mandrel being provided with a lateral slot in a wall portion thereof of slight axial displacement from said ledge for insertion and withdrawal of said disks.

12. The combination of elements defined in claim l1 and including a cross-head connected to said cylinder for moving the latter relative to said mandrel and uid coolant means connected to said cross-head including a tube extending axially to the vicinity of said disks for cooling the latter during irradiation thereof` 13. The combination of elements defined in claim l1 and including a stationary bar secured to said mandrel, a cross-head connected to said cylinder, and a handle pivoted to said cross-head.

and having a link connection with said bar whereby relative movement of said bar to said handle is eiective to move said cylinder axially of said mandrel.

14. The combination of elements defined in claim ll and including a stationary bar secured to said mandrel, a cross-head connected to said cylinder, a handle pivoted to said cross-head and having a link connection with said bar and adinstable means extending between said handle and said bar for adjusting the spacing between said ledge and the peripheral end portion of said cylinder.

CARROLL M. GORDON. CHARLES A. CORUM.

References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date 2,361,722 Von Ardenne Oct. 31, 1944 2,362,515 Weigend Nov. 14, 1944 2,531,065 Livingood et al. Nov. 21, 1950 2,533,701 Watt et al. Dec. 1 2, 1950V 2,543,825 Ben et al. Mar. 6, 1951 2,626,359 Weber, Jr. Jan. 20, 1953 

